1. Field of the Invention
This invention relates to electro-magnetic rappers which are used on precipitators. Such structures of this type, generally, employ the use of a wear guide which reduces rapper liner wear.
2. Description of the Related Art
Precipitators are used for the collection of particulate matter generated during combustion. It is very important for the precipitator to perform at its highest level because it is the last line of defense for preventing environmental emissions into the atmosphere. Every component in the precipitator must be operating at 100% to ensure proper collection of particulate matter.
The function of the electro-magnetic rapper is to generate a shock wave that will dislodge collected matter in such a manner that it is gently dropped to the bottom of the precipitator where it will be removed. If the rappers are not working at a consistently high level, emissions to the atmosphere will be greater than desired.
It has been observed that rappers operate at various levels of efficiency due to the severity of rapper liner wear. In fact, it has been observed that severely worn liners will not allow the piston to move at all. This is because as the rapper liner wears due to friction, the magnetic attraction between the piston and the flange at the base of the housing becomes greater. When the magnetic attraction increases, the wear of the liner is accelerated. The two forces compliment each other and this continues until there is a piston-to-flange contact. When this happens, the rapper is at the end of its service life and needs to be replaced.
It is known, in electro-magnetic rappers to employ various internal wear guides. Exemplary of such prior art are U.S. Pat. No. 2,985,802 ('802) to J. W. Drenning, entitled "Magnetic Impulse Rapper" and U.S. Pat. No. 3,477,124 ('124) to W. E. Archer et al., entitled "Method of Making an Electrical Rapper". While the '802 and '124 patents employ the use of internal wear guides, the reciprocating action of the piston within the rapper still can erode the wear guides and, therby adversely affect the performance of the rapper. Consequently, a more advantageous rapper, then would be presented if the performance of the rapper could be improved.
It is apparent from the above that there exists a need in the art for an electro-magnetic rapper which at least equals the performance characteristics of the known rappers, but which at the same time eliminates the magnetic attraction between the piston and the flange. It is the purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure.